KR102513317B1 - Non-oriented electrical steel sheet and method for manufacturing the same - Google Patents

Abstract

In the non-oriented electrical steel sheet according to an embodiment of the present invention, Si: 1.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, Cr: 0.01 to 0.2%, Sn: 0.01 to 0.02% , and Sb: 0.01 to 0.02%, including a steel sheet base material containing Fe and other unavoidable impurities and an insulating film located on the surface of the steel sheet base material, the Mn concentration at a depth of 50 μm from the surface of the steel sheet base material to the inside of the base material is [Mn50], and the Mn concentration of the insulating film is [Mn film], the following formula 1 is satisfied before stress relief annealing, and the following formula 2 is satisfied after stress relief annealing.
[Equation 1]
0.01 ≥ [Mn film] / [Mn50]
[Equation 2]
2 ≥ [Mn film] / [Mn50] ≥ 0.05

Description

Non-oriented electrical steel sheet and its manufacturing method {NON-ORIENTED ELECTRICAL STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME}

One embodiment of the present invention relates to a non-oriented electrical steel sheet and a manufacturing method thereof. Specifically, one embodiment of the present invention relates to a non-oriented electrical steel sheet in which the adhesion of an insulating film is improved by properly adjusting the Cr content to prevent Mn diffusion into the insulating film during stress relief annealing, and a manufacturing method thereof.

Non-oriented electrical steel sheets are mainly used in motors that convert electrical energy into mechanical energy, and excellent magnetic properties of non-oriented electrical steel sheets are required to demonstrate high efficiency in the process. In particular, as eco-friendly technology has recently been attracting attention, it is considered very important to increase the efficiency of motors that account for the majority of the total electrical energy consumption. To this end, the demand for non-oriented electrical steel sheets having excellent magnetic properties is also increasing.

The magnetic properties of non-oriented electrical steel are mainly evaluated by iron loss and magnetic flux density. Iron loss means energy loss that occurs at a specific magnetic flux density and frequency, and magnetic flux density means the degree of magnetization obtained under a specific magnetic field. The lower the iron loss, the more energy efficient motors can be manufactured under the same conditions, and the higher the magnetic flux density, the smaller the motor or the lower the copper loss. It is important.

The characteristics of the non-oriented electrical steel sheet to be considered also vary according to the operating conditions of the motor. As a criterion for evaluating the characteristics of non-oriented electrical steel used in motors, many motors regard W15/50, which is the iron loss when a 1.5T magnetic field is applied at a commercial frequency of 50Hz, as the most important. However, not all motors for various purposes consider W15/50 core loss as the most important, and depending on the main operating conditions, core loss at different frequencies or applied magnetic fields is evaluated. In particular, in non-oriented electrical steel sheets used in recent electric vehicle drive motors, magnetic properties are often important at low fields of 1.0T or less and high frequencies of 400 Hz or more. characteristics will be evaluated.

In order to manufacture products such as motors or transformers from non-oriented electrical steel sheet, the non-oriented electrical steel sheet must be slit into a specific shape. In this process, stress is applied to the non-oriented electrical steel sheet, and stress relief annealing is performed to remove this stress.

During the stress relief annealing process, the Mn component in the steel sheet is diffused into the insulating film, which causes a decrease in adhesion between the steel sheet and the insulating film. Attempts have been made to suppress the diffusion of Mn by adding Sb and Sn and controlling the content relationship between Al and Mn, but these attempts have limitations. The suppression of diffusion of Mn through the formation of a surface segregated element layer and a surface oxide layer had little effect, resulting in a weakening of the bonding force between the insulating coating and the base material.

One embodiment of the present invention is to provide a non-oriented electrical steel sheet and a manufacturing method thereof. Specifically, in one embodiment of the present invention, the content of Cr is appropriately controlled to prevent Mn diffusion into the insulation film during stress relief annealing, thereby improving the adhesion of the insulation film to provide a non-oriented electrical steel sheet and a manufacturing method thereof. .

In the non-oriented electrical steel sheet according to an embodiment of the present invention, Si: 1.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, Cr: 0.01 to 0.2%, Sn: 0.01 to 0.02% , and Sb: 0.01 to 0.02%, including a steel sheet base material containing Fe and other unavoidable impurities and an insulating film located on the surface of the steel sheet base material, the Mn concentration at a depth of 50 μm from the surface of the steel sheet base material to the inside of the base material is [Mn50], and the Mn concentration of the insulating film is [Mn film], the following formula 1 is satisfied before stress relief annealing, and the following formula 2 is satisfied after stress relief annealing.

[Equation 1]

0.01 ≥ [Mn film] / [Mn50]

[Equation 2]

2 ≥ [Mn film] / [Mn50] ≥ 0.05

The steel sheet base material may further include at least one of P: 0.1% by weight or less and Ti: 0.1% by weight or less.

The steel sheet base material may further include one or more of C: 0.007 wt% or less, S: 0.01 wt% or less, and N: 0.01 wt% or less.

The steel plate base material may further include one or more of Cu and Ni in an amount of 0.05% by weight or less, respectively.

Stress relief annealing may be performed at a temperature of 700° C. to 850° C. for 10 minutes to 300 minutes.

An oxide layer is present in an inward direction from the surface of the steel sheet base material, and the thickness of the oxide layer may be 10 to 50 nm.

The oxide layer may include 5 to 50% by weight of O.

The insulating film before stress relief annealing may include Mn: 0.01% by weight or less.

After stress relief annealing, the insulating film may include 0.03 to 10 wt % of Mn.

In the method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention, by weight, Si: 1.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, Cr: 0.01 to 0.2%, Sn: 0.01 to 0.02%, and Sb: 0.01 to 0.02%, and preparing a hot-rolled sheet by hot rolling a slab containing Fe and other unavoidable impurities; Cold-rolling a hot-rolled sheet to prepare a cold-rolled sheet; It includes the step of final annealing the cold-rolled sheet and the step of forming an insulating film on the final annealed steel sheet. ], the following formula 1 is satisfied before stress relief annealing, and the following formula 2 is satisfied after stress relief annealing.

[Equation 1]

0.01 ≥ [Mn film] / [Mn50]

[Equation 2]

2 ≥ [Mn film] / [Mn50] ≥ 0.05

The step of annealing the cold-rolled sheet may be annealed at a temperature of 700 ° C to 1100 ° C for 10 to 1000 seconds.

According to one embodiment of the present invention, by including Cr within a certain range, diffusion of the Mn component included in the steel sheet base material to the insulation film is prevented during the stress relief annealing process, thereby improving the bonding strength between the insulation film and the steel sheet base material even after stress relief annealing. keep

Through this, the performance of eco-friendly automobile motors, high-efficiency home appliance motors, and super premium electric motors can be further improved through stress relief annealing.

1 is a schematic view of a cross section of a non-oriented electrical steel sheet according to an embodiment of the present invention.

Terms such as first, second and third are used to describe, but are not limited to, various parts, components, regions, layers and/or sections. These terms are only used to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first part, component, region, layer or section described below may be referred to as a second part, component, region, layer or section without departing from the scope of the present invention.

The terminology used herein is only for referring to specific embodiments and is not intended to limit the present invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. The meaning of "comprising" as used herein specifies particular characteristics, regions, integers, steps, operations, elements and/or components, and the presence or absence of other characteristics, regions, integers, steps, operations, elements and/or components. Additions are not excluded.

When a part is referred to as being “on” or “on” another part, it may be directly on or on the other part or may be followed by another part therebetween. In contrast, when a part is said to be “directly on” another part, there is no intervening part between them.

In addition, unless otherwise specified, % means weight%, and 1ppm is 0.0001 weight%.

In one embodiment of the present invention, the meaning of further including an additional element means replacing and including iron (Fe) as much as the additional amount of the additional element.

Although not defined differently, all terms including technical terms and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Terms defined in commonly used dictionaries are additionally interpreted as having meanings consistent with related technical literature and currently disclosed content, and are not interpreted in ideal or very formal meanings unless defined.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

1 schematically shows a cross section of a non-oriented electrical steel sheet according to an embodiment of the present invention. As shown in FIG. 1 , the non-oriented electrical steel sheet 100 includes a steel sheet base material 10 and an insulating film 20 positioned on the surface of the steel sheet base material 10 . An oxide layer 30 formed in an inward direction from the surface of the base material may exist in the steel plate base material 10 .

The steel sheet base material 10 according to an embodiment of the present invention contains Si: 1.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, Cr: 0.01 to 0.2%, Sn: 0.01 to 0.02% by weight. %, and Sb: 0.01 to 0.02%, the balance including Fe and other unavoidable impurities.

Hereinafter, the reason for limiting the components of the steel plate base material 10 will be explained.

Si: 1.0 to 6.5% by weight

Silicon (Si, silicon) serves to lower the iron loss by increasing the specific resistance of the material, and when too little is added, the effect of improving the high frequency iron loss may be insufficient. Conversely, if too much is added, the hardness of the material increases and the cold rolling property is extremely deteriorated, resulting in poor productivity and punching performance. Therefore, Si may be added within the above range. More specifically, it may include 2.0 to 5.0% by weight. More specifically, it may include 3.0 to 4.0% by weight.

Al: 0.1 to 1.3% by weight

Aluminum (Al) serves to lower iron loss by increasing the resistivity of the material. If too little is added, there is no effect on reducing high-frequency iron loss, and fine nitrides may be formed to deteriorate magnetism. Conversely, if too much is added, it can cause problems in all processes such as steelmaking and continuous casting, greatly reducing productivity. Therefore, Al may be added within the above range. More specifically, it may contain 0.5 to 1.2% by weight. More specifically, it may contain 0.7 to 1.0% by weight.

Mn: 0.3 to 2.0% by weight

Manganese (Mn) is an element that serves to improve iron loss and form sulfides by increasing the resistivity of materials. If too little Mn is added, sulfides may be finely precipitated to deteriorate magnetism. Conversely, if too much Mn is added, the formation of {111} texture, which is unfavorable to magnetism, may be promoted and the magnetic flux density may decrease. Therefore, Mn may be added within the above-mentioned range. More specifically, 0.5 to 1.5 wt % of Mn may be included.

In one embodiment of the present invention, the specific resistance may be 55 to 80 μΩ cm.

Cr: 0.010 to 0.200% by weight

Chromium (Cr) serves to reduce iron loss by increasing the resistivity of the material. It also serves to prevent diffusion of Mn from the base material into the insulating coating in the stress relief annealing step. Therefore, Cr may be added within the above range. More specifically, it may include 0.050 to 0.150% by weight. More specifically, it may include 0.050 to 0.100% by weight.

Sn, Sb: 0.01 to 0.02% by weight, respectively

Tin (Sn) and antimony (Sb) are segregated elements at grain boundaries, suppressing the diffusion of nitrogen through grain boundaries, suppressing {111} texture harmful to magnetism, and increasing advantageous {100} texture for magnetic properties. added to improve When too much Sn and Sb are added, crystal grain growth is hindered, resulting in deterioration of magnetism and poor rolling properties. Therefore, Sn and Sb may be added within the above range.

The steel plate base material 10 may further include at least one of P: 0.1 wt% or less and Ti: 0.1 wt% or less. More specifically, P: 0.1% by weight or less and Ti: 0.1% by weight or less may be further included. As described above, when an additional element is further included, Fe, which is the remainder, is replaced and included.

P 0.100% by weight or less

Phosphorus (P) not only serves to increase the specific resistance of the material, but also segregates at the grain boundary to improve the texture to increase the specific resistance and lower the iron loss, so it can be additionally added. However, too much addition of P results in the formation of a texture that is unfavorable to magnetism, so there is no effect on improving the texture, and excessive segregation at grain boundaries reduces rollability and workability, making production difficult. Therefore, P may be added in the above range. More specifically, 0.001 to 0.090% by weight of P may be included. More specifically, 0.005 to 0.085% by weight of P may be included.

Ti: 0.0100% by weight or less

Titanium (Ti) suppresses crystal grain growth by forming fine carbides and nitrides, and it is preferable to contain a small amount of titanium (Ti) because it interferes with the movement of magnetic domains due to increased carbides and nitrides as it is added in large amounts. Therefore, Ti may be added within the above range. More specifically, 0.0001 to 0.0050 wt % of Ti may be included.

The steel plate base material 10 may further include one or more of C: 0.007 wt% or less, S: 0.01 wt% or less, and N: 0.01 wt% or less. More specifically, C: 0.007% by weight or less, S: 0.01% by weight or less, and N: 0.01% by weight or less may be further included.

C: 0.007% by weight or less

When carbon (C) is added in large quantities, it expands the austenite region, increases the phase transformation period, and suppresses the grain growth of ferrite in the annealing area to increase iron loss. When used after processing from a product to an electrical product, iron loss is increased by magnetic aging. Therefore, C may be added within the above range. More specifically, 0.005% by weight or less of C may be included.

S: 0.0100% by weight or less

Sulfur (S) is preferably added as low as possible because it forms fine sulfides inside the base material to suppress crystal grain growth and weaken iron loss. When a large amount of S is included, it may combine with Mn to form precipitates or cause high temperature brittleness during hot rolling. Accordingly, S may be further included in an amount of 0.0100% by weight or less. Specifically, it may further include 0.0050% by weight or less of S. More specifically, 0.0001 to 0.0040% by weight of S may further be included.

N: 0.0100% by weight or less

Nitrogen (N) is preferably contained in a small amount because it forms nitride by strongly defecting with Al, Ti, etc. to suppress crystal grain growth, and interferes with magnetic domain movement when precipitated. Therefore, N may be added in the above range. More specifically, N may be included in an amount of 0.005% by weight or less.

The steel plate base material 10 may further include at least one of Cu and Ni in an amount of 0.05% by weight or less, respectively.

The steel plate base material 10 may further include 0.01% by weight or less of one or more of Zr, Mo, and V, respectively.

Cu and Ni, which are elements that are inevitably added in the steelmaking process, react with impurity elements to form fine sulfides, carbides, and nitrides, which have a detrimental effect on magnetism, so their contents are limited to 0.05% by weight or less, respectively. In addition, since Zr, Mo, V, etc. are also strong carbonitride forming elements, it is preferable not to add them as much as possible, and each content is 0.01% by weight or less.

The balance includes Fe and unavoidable impurities. As for the unavoidable impurities, they are impurities introduced during the steelmaking step and the grain-oriented electrical steel sheet manufacturing process, and since they are well known in the relevant field, a detailed description thereof will be omitted. In one embodiment of the present invention, the addition of elements other than the above-described alloy components is not excluded, and may be variously included within a range that does not impair the technical spirit of the present invention. When additional elements are included, they are included in place of Fe, which is the remainder.

In one embodiment of the present invention, diffusion of Mn into the insulating film 20 can be suppressed in the stress relief annealing step through the addition of Cr to the steel sheet base material 10 .

If Mn diffusion into the insulating film 20 increases and the Mn component of the coating is too high, the insulating properties of the insulating coating may deteriorate. In addition, the bonding force between the coating and the base material may be weakened.

When the Mn concentration at a depth of 50 μm from the surface of the steel sheet base material 10 to the inside of the base material is [Mn50] and the Mn concentration of the insulation film 20 is [Mn film], the following formula 1 is satisfied before stress relief annealing, , after stress relief annealing, the following equation 2 is satisfied.

[Equation 1]

0.01 ≥ [Mn film] / [Mn50]

[Equation 2]

2 ≥ [Mn film] / [Mn50] ≥ 0.05

Stress relief annealing may be performed at a temperature of 700° C. to 850° C. for 10 minutes to 300 minutes. More specifically, it may be performed at a temperature of 800 to 850 °C for 30 minutes to 120 minutes. More specifically, it may be performed for 60 minutes at a temperature of 825 °C.

By adding Cr to the steel plate base material 10, an oxide layer 30 is formed from the surface of the steel plate base material 10 toward the inside of the base material. That is, the oxide layer 30 exists at the interface between the steel plate base material 10 and the insulating coating 20 . This oxide layer 30 serves to prevent diffusion of Mn from the steel sheet base material 10 to the insulating coating 20 . The oxide layer 30 refers to a portion having an oxygen content of 40% by weight or more, and is formed from the surface to the inside as oxygen in the atmosphere penetrates into the steel sheet as it is exposed to oxygen in the manufacturing process.

The thickness of the oxide layer 30 divided in this way may be 10 to 50 nm. If the oxide layer 30 is formed too thin, it is difficult to adequately prevent the aforementioned Mn diffusion. If the oxide layer 30 is formed too thick, magnetic properties may be deteriorated. Thus, the oxide layer 30 may exist with a thickness within the aforementioned range.

The oxide layer 30 may include 5 to 50% by weight of O. As described above, the oxygen content in the oxide layer 30 has a concentration gradient in the thickness direction, and the above range means the average content in the thickness direction of the oxide layer 30. Other components may be the same as those of the steel plate base material 10 .

The insulating film 20 is located on the surface of the steel sheet base material 10 . The insulating film 20 serves to insulate between the non-oriented electrical steel sheets when a product is manufactured by laminating the non-oriented electrical steel sheets. The insulating film 20 may be treated with organic, inorganic, and organic/inorganic composite films, and may be formed by treating with other insulating film materials.

For example, when the insulating film 20 is formed using a phosphate-based insulating film composition, the insulating film may include P: 5 to 50% by weight and Mn: 0.01% by weight or less. As such, the insulating film 20 before stress relief annealing contains a small amount of Mn. The remainder may be O. It may further include 1 to 10% by weight of Si.

Meanwhile, the insulation film after stress relief annealing may include 0.03 to 1.50 wt% of Mn in the steel sheet base material 10 due to partial diffusion. The remaining components may be the same as before stress relief annealing. That is, after stress relief annealing, the insulating film 20 may include P: 5 to 50% by weight and Mn 0.03 to 10.00% by weight. The remainder may be O. It may further include 1 to 10% by weight of Si.

A method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention includes the steps of hot rolling a slab to prepare a hot rolled sheet; Cold-rolling a hot-rolled sheet to prepare a cold-rolled sheet; It includes the step of final annealing the cold-rolled sheet and the step of forming an insulating film on the final annealed steel sheet.

First, a slab is hot rolled.

Since the alloy components of the slab have been described in the above-described alloy components of the non-oriented electrical steel sheet, overlapping descriptions will be omitted. Since the alloy components are not substantially changed during the manufacturing process of the non-oriented electrical steel sheet, the alloy components of the non-oriented electrical steel sheet and the slab are substantially the same.

Specifically, the slab contains Si: 1.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, Cr: 0.01 to 0.2%, Sn: 0.01 to 0.02%, and Sb: 0.01 to 0.02% by weight%. and the balance includes Fe and other unavoidable impurities.

Since the other additional elements have been described in the alloy components of the non-oriented electrical steel sheet, overlapping descriptions are omitted.

The slabs may be heated prior to hot rolling. The heating temperature of the slab is not limited, but the slab can be heated to 1100 to 1250 ° C. If the slab heating temperature is too high, precipitates that harm magnetism may be re-dissolved and finely precipitated after hot rolling.

Next, a hot-rolled sheet is manufactured by hot-rolling the slab. The thickness of the hot-rolled sheet may be 2 to 3.0 mm.

After the step of manufacturing the hot-rolled sheet, a step of annealing the hot-rolled sheet may be further included. Hot-rolled sheet annealing is preferably performed in the manufacture of a high-grade electrical steel sheet without phase transformation, and is effective in improving the magnetic flux density by improving the texture of the final annealed sheet.

At this time, the step of annealing the hot-rolled sheet may be annealed at a temperature of 850 to 1200 ℃. If the hot-rolled sheet annealing temperature is too low or less, the structure does not grow or grows finely, making it difficult to expect the effect of increasing the magnetic flux density. If the annealing temperature of the hot-rolled sheet is too high, the magnetic properties are rather deteriorated, and the rolling workability may be deteriorated due to deformation of the plate shape. Hot-rolled sheet annealing is performed to increase orientation favorable to magnetism, if necessary, and can be omitted. The annealed hot-rolled sheet may be pickled.

Next, the hot-rolled sheet is cold-rolled to manufacture a cold-rolled sheet. Cold rolling is final rolling to a thickness of 0.15 mm to 0.65 mm. If necessary, secondary cold rolling may be performed after primary cold rolling and intermediate annealing, and the final reduction ratio may be in the range of 50 to 95%.

Next, the cold-rolled sheet is subjected to final annealing. The final annealing is performed for 10 to 1000 seconds within the range of 700 to 1100 ° C so that the grain size in the cross section of the steel sheet is 50 to 150 μm. If the final annealing temperature is too low, the crystal grains are small and iron loss may be deteriorated. If the temperature is too high, the crystal grains are coarsened and the abnormal vortex loss increases, resulting in an increase in total iron loss.

After the final annealing, all (99% or more) of the steel sheet processed by cold rolling can be recrystallized.

A heating rate up to a soaking temperature during final annealing may be 30 to 150° C./sec. When the heating rate is appropriately controlled, the oxide layer is formed thinly and densely, and diffusion of Mn can be prevented.

In the final annealing step, the cold-rolled sheet may be annealed under an atmosphere containing 40 vol% or less of hydrogen (H ₂ ) and 60 vol% or more of nitrogen, and having a dew point of 0 to -40 °C. Specifically, annealing may be performed in an atmosphere containing 0 to 10 vol% of hydrogen and 90 to 100 vol% of nitrogen. When the annealing atmosphere is appropriately controlled, the oxide layer is formed thinly and densely, so that diffusion of Mn can be prevented.

Next, after final annealing, an insulating film may be formed. The insulating coating may be treated with organic, inorganic, and organic/inorganic composite coatings, and may be treated with other insulating coatings. For example, it may be formed by applying an insulating film-forming composition containing 40 to 70% by weight of metal phosphate and 0.5 to 10% by weight of silica.

Next, a step of stress relief annealing may be further included. The stress relief annealing step is performed at a temperature of 700° C. to 850° C. for 10 minutes to 300 minutes.

Hereinafter, the present invention will be described in more detail through examples. However, these examples are only for exemplifying the present invention, and the present invention is not limited thereto.

Example 1

A slab composed of Table 1 below and the balance of Fe and other unavoidably added impurities was prepared. The slab was heated to 1150 ° C., and hot finish rolling was performed at 850 ° C. to produce a hot-rolled sheet having a thickness of 2.3 mm. The hot-rolled hot-rolled sheet was annealed at 1100° C. for 4 minutes and then pickled. Thereafter, the sheet was cold-rolled to a thickness of 0.27 mm, heated at 100° C./sec, and finally annealed at 970° C. for 5 minutes in an atmosphere containing nitrogen. The insulating film was formed to a thickness of 0.5 μm using an insulating film composition containing 50% by weight of Al phosphate and 5% by weight of silica.

Thereafter, annealing was performed at 825° C. for 1 hour to relieve stress. Through this, a finally stress-removed non-oriented electrical steel sheet was manufactured. The depth direction component was measured three times with a glow discharge spectrometer, and the average values of the Mn film and Mn50 are shown in Table 2 below according to the experimental conditions.

Adhesion was measured by the Crosscut Test (ASTM D3359) method.

(weight%) C Si Al Mn Cr Ti Sn Sb Comparative Example 1 0.0035 3.0 0.7 0.3 0.001 0.003 0.015 0.015 Example 1 0.0035 3.0 0.7 0.3 0.050 0.003 0.015 0.015 Example 2 0.0035 3.0 0.7 0.3 0.100 0.003 0.015 0.015 Comparative Example 2 0.0035 3.0 0.7 0.5 0.001 0.003 0.015 0.015 Example 3 0.0035 3.0 0.7 0.5 0.050 0.003 0.015 0.015 Example 4 0.0035 3.0 0.7 0.5 0.100 0.003 0.015 0.015 Comparative Example 3 0.0035 3.0 0.7 1.5 0.001 0.003 0.015 0.015 Example 5 0.0035 3.0 0.7 1.5 0.050 0.003 0.015 0.015 Example 6 0.0035 3.0 0.7 1.5 0.100 0.003 0.015 0.015

Before stress relief annealing After stress relief annealing [Mn film] [Mn50] [Mn film] / [Mn50] [Mn film] [Mn50] [Mn film] / [Mn50] adhesion Comparative Example 1 0.001 0.29 0.003 1.35 0.28 4.821 4B Example 1 0.001 0.3 0.003 0.35 0.32 1.094 5B Example 2 0.001 0.3 0.003 0.03 0.33 0.091 5B Comparative Example 2 0.001 0.48 0.002 3.23 0.49 6.592 3B Example 3 0.001 0.5 0.002 0.89 0.52 1.712 5B Example 4 0.001 0.51 0.002 0.06 0.55 0.109 5B Comparative Example 3 0.001 1.49 0.001 3.52 1.45 2.428 3B Example 5 0.001 1.52 0.001 1.32 1.56 0.846 5B Example 6 0.001 1.51 0.001 0.35 1.52 0.23 5B

As shown in Tables 1 and 2, it can be confirmed that the examples containing an appropriate amount of Cr have an appropriate oxide layer, suppress the diffusion of Mn into the insulating film after stress relief annealing, and have excellent adhesion. On the other hand, too little Cr It can be seen that the comparative example containing or containing too much Mn did not properly form an oxide layer, and a large amount of Mn diffused into the insulating film after stress relief annealing, resulting in poor adhesion.

The present invention is not limited to the examples and can be manufactured in various different forms, and those skilled in the art to which the present invention pertains may change other specific forms without changing the technical spirit or essential features of the present invention. It will be appreciated that it can be implemented. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting.

100: non-oriented electrical steel sheet, 10: steel sheet base material,
20: insulating film, 30: oxide layer

Claims (12)

Si: 1.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, Cr: 0.01 to 0.2%, Sn: 0.01 to 0.02%, and Sb: 0.01 to 0.02%, balance Fe and other unavoidable impurities, and
Including an insulating film located on the surface of the steel sheet base material,
An oxide layer is present in an inward direction from the surface of the steel sheet base material, and the thickness of the oxide layer is 10 to 50 nm,
When the Mn concentration at a depth of 50 μm from the surface of the base material to the inside of the base material is [Mn50] and the Mn concentration of the insulation film is [Mn film], the following Equation 1 is satisfied before stress relief annealing, and after stress relief annealing A non-oriented electrical steel sheet that satisfies Equation 2 below.
[Equation 1]
0.01 ≥ [Mn film] / [Mn50]
[Equation 2]
2 ≥ [Mn film] / [Mn50] ≥ 0.05 According to claim 1,
The steel sheet base material is P: 0.1% by weight or less and Ti: 0.1% by weight or less of at least one of the non-oriented electrical steel sheet further comprises. According to claim 1,
The steel sheet base material is C: 0.007% by weight or less, S: 0.01% by weight or less, and N: 0.01% by weight or less of at least one of the non-oriented electrical steel sheet further comprises. According to claim 1,
The steel sheet base material is a non-oriented electrical steel sheet further comprising at least one of Cu and Ni at 0.05% by weight or less, respectively. According to claim 1,
The base material of the steel sheet is a non-oriented electrical steel sheet further comprising at least one of Zr, Mo and V in an amount of 0.01% by weight or less, respectively. According to claim 1,
The stress relief annealing is performed at a temperature of 700 ° C. to 850 ° C. for a time of 10 minutes to 300 minutes. delete According to claim 1,
The oxide layer is a non-oriented electrical steel sheet containing 5 to 50% by weight of O. According to claim 1,
The insulating coating before the stress relief annealing is a non-oriented electrical steel sheet containing 0.1% by weight or less of Mn. According to claim 1,
After the stress relief annealing, the insulating coating is a non-oriented electrical steel sheet containing 0.03 to 10% by weight of Mn. Si: 1.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, Cr: 0.01 to 0.2%, Sn: 0.01 to 0.02%, and Sb: 0.01 to 0.02%, balance Fe and preparing a hot-rolled sheet by hot-rolling a slab containing other unavoidable impurities;
manufacturing a cold-rolled sheet by cold-rolling the hot-rolled sheet;
Final annealing of the cold-rolled sheet and
Forming an insulating film on the final annealed steel sheet,
In the step of final annealing the cold-rolled sheet, the heating rate to the soaking temperature is 30 to 150 ° C / sec,
In the final annealing step, the cold-rolled sheet is annealed under an atmosphere containing 0 to 10 vol% of hydrogen (H2) and 90 to 100 vol% of nitrogen and having a dew point of 0 to -40 ° C,
When the Mn concentration at a depth of 50 μm inward from the surface of the steel sheet is [Mn50] and the Mn concentration of the insulation film is [Mn film], the following formula 1 is satisfied before stress relief annealing, and the following after stress relief annealing A method for manufacturing a non-oriented electrical steel sheet that satisfies Equation 2.
[Equation 1]
0.01 ≥ [Mn film] / [Mn50]
[Equation 2]
2 ≥ [Mn film] / [Mn50] ≥ 0.05 According to claim 11,
Annealing the cold-rolled sheet is a method of manufacturing a non-oriented electrical steel sheet annealing for 10 to 1000 seconds at a temperature of 700 ℃ to 1100 ℃.

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